Fat and fast.

One of the most common misconceptions of fat bikes is that they're slow. Well, we suppose they're slow relative to a time-trial road rig with 23mm tires at 140psi, but we'd like to see those pencil-neck rims ride across sand and snow where there's no tarmac or even established trails. Still, it's nice to have the stiff efficiency of carbon fiber between your engine and the terrain, and Borealis' Crestone X01 Complete Fat Bike adapts all the carbon technology of high-end road frames for efficient, stiff pedaling across the land that begins where the trail ends.

The Crestone's carbon chassis may not be noticeably stiffer than the brand's other carbon frame, the Echo, but Borealis does claim that it's 150g lighter. This indicates to us that it's built with a higher grade carbon that requires less material to hit the same standards of stiffness and durability. Lower weight equates to fewer grams to propel and less fatigue over the course of a weekend bikepacking trip, and it's still got the huge, plush tires to ensure that the stiffness of carbon doesn't translate to a harsh, abusive ride.

The Crestone enjoys some other differences from the Echo, especially in the frame geometry. The Crestone has a slightly shorter top tube and stack, which combine with an equally subtle increase in head tube angle to tighten up the bike's steering. The frame is mated to the kind of SRAM X01 drievtrain we'd expect from a full-carbon, six-inch, enduro race sled, which means the Crestone X01 may be the most efficient fat bike we've had the pleasure of rolling through our doors, past the trailhead, and straight out into the wilderness.